WEBVTT
Kind: captions
Language: en

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Hearing is incredible.

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Think about it: a tiny little bit of tissue
in your ear, a tenth of a millimetre thick,

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moves in response to changes in air pressure,

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and converts them into
tiny vibrations in fluid,

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and then those get converted into electrochemical
impulses that go the brain,

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where they are somehow decoded into
what you experience as sound.

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And if all of that is working properly,

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then you're able to pick out one source of
sound from another, in 3D space,

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and your brain is optimised
to pick out words and language

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even through huge amounts of noise.

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It'll even filter out constant, steady noise
like a fan or the wind whistling through trees.

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To give an idea of
just how difficult a task that is:

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this is the waveform of the sound
that's on this video.

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Same information, just presented differently,

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but it's not something that you can
make sense of with your eyes.

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And it's not like your eardrum only resonates
at a few frequencies.

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Human hearing in a
healthy, young person runs from

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somewhere up around 20,000 cycles a second,
all the way down to 20.

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Which means the eardrum can pick up
air movements with wavelengths

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that range from a couple of centimetres for
high frequencies,

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to 10 or 20 metres for really low bass.

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The sort of low, rumbling bass that you
would get from, say, a jet engine.

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Just over there is Amsterdam Schiphol airport.

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In terms of aircraft flying in and out,
it's the busiest airport in Europe.

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Six runways. Two control towers,

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one just for the new runway that's over there
that opened in 2003.

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That runway is five kilometres away from the
terminal.

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If you look at aerial photos,

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you can see plane after plane after plane
lined up on a fifteen-minute taxi,

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including going on a bridge
across a road and a canal.

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It was raining when my plane landed, but I
just about got that shot out the window.

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But there was one residential area,
just back there, where there was

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nothing but flat ground between those houses
and the back end of jet engines.

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I mean, of course it was flat ground,
it's the Netherlands,

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but there was one spot just back there where it
got significantly louder

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for the people who lived there.

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And those local residents were not happy.

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Of course, the one day I'm here,

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they're actually landing on that runway,
not taking off

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so the engines are pointed the other way,
but the point still stands.

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The local residents were not happy.

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This is the solution.

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Well, not a solution, 
at least something to help.

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This is a park that serves two purposes:
one, to be land art,

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the sort of high-concept big sculpture
that's created

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by moving enormous amounts of earth
and rock.

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This was designed by an artist.

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I mean, I'd send up a drone to show you,
but, you know, airport.

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But the second purpose is sound dampening.

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These ridges are metres apart,
roughly, very roughly,

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around the same wavelength as the low rumble
you get from a jet engine.

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Not exact, of course, but in the same order
of magnitude,

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close enough to be disruptive.

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So rather than the sound waves just rolling
over the land,

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instead they're scattered in all directions,
up and away, not onwards.

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Not perfectly, not even close, but enough
to bring the noise level at those houses

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back down within acceptable limits.

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The architects claim that
one of the inspirations for this

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was people noticing that the engine noise
sounded quieter when the fields were ploughed.

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Because, yes, your brain can filter out
constant, steady noise.

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It can even, over time, get used to filtering
out intermittent, loud noise,

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like living next to an airport.

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But that filtering job is a lot easier if
the noise would just be a little less loud.